In recent years, under circumstances where environmental problems caused by plastic waste have been brought to the fore and realization of the society with an environmentally-sound material cycle of a global scale has been greatly desired, a biodegradable plastic decomposed into water and carbon dioxide by the action of microorganisms after use has drawn attention. Examples of the biodegradable plastic include 1) microorganism-produced aliphatic polyesters such as polyhydroxyalkanoate (hereinafter referred to as PHA), 2) petroleum-derived resin such as polylactic acid, polycaprolactone, polybutylene adipate terephthalate, polybutylene succinate adipate, and polybutylene succinate, and 3) natural polymers such as starch and cellulose acetate, and the like. However, among petroleum-derived aliphatic polyesters, the polylactic acid and the polycaprolactone have a problem with heat resistance and the natural polymers have problems in that the polymers are non-thermoplastic or have poor water resistance. Furthermore, from the viewpoint of a reduction in carbon dioxide emission, the society has increasingly become a society where the use of non-petroleum-derived resin with high biomass degree is desired. Then, the use of a biodegradable resin which contains plant materials and in which the proportion of the microorganism-produced aliphatic polyester which does not increase the carbon dioxide on the earth, i.e., carbon-neutral, has been desired.
Heretofore, as the film and the sheet containing the microorganism-produced aliphatic polyester, a film containing poly(3-hydroxybutyrate-co-3-hydroxyhexanoate, Abbreviation: PHBH) produced from microorganisms (Patent Document 1), a sheet containing a resin composition containing petroleum-derived resin such as polybutylene adipate terephthalate, polybutylene succinate adipate, polybutylene succinate, and polycaprolactone, and PHBH (Patent Document 2) and the like are disclosed.
However, when the microorganism-produced aliphatic polyester such as PHBH, and the resin composition containing the same have been molded into a film or a sheet by a blown film method or a T-die extrusion method, the tear strength in the MD direction (the withdrawal direction in molding) of the obtained film or the obtained sheet has been insufficient.